All Praise be to Allaah.
To the noble inquirer:
You have traversed an important part of the path to the truth and directing yourself towards it. From what I have been able to gather from your question, I understand that you wish to embrace Islam but what is preventing you from doing so is fear for your sick mother's health upon hearing the news. I want you to know that overcoming this obstacle is an easy matter, as it is possible for you in a practical way, to conceal your acceptance of Islam and not divulge it. You are not required to announce your acceptance of Islam in an Islamic center or anywhere else; all that is required is the pronouncing of the two testimonies of faith (see question(s) ) and the initiation of practicing the rites of the religion. You can pray in private, undisclosed places, for example. In addition, fasting will not be difficult as you can easily advance any appropriate excuse for not eating if something is offered to you during the daylight hours of the month of fasting.
Now, I would like to remind you of two things:
Firstly, that the driving factor and underlying truth regarding wanting to embrace the religion must be to gain the pleasure and acceptance of your Lord--Allaah, the Most Glorified and All-High, who does not accept any religion other than Islam, as He has said in his Glorious Book (the Qur'aan), [interpretation of the meaning]: "And whoever seeks a religion other than Islam--it will never be accepted from him, and in the Hereafter he will be among the losers." (The Family of Imran, verse 3:85) It has been narrated by Abu Hurairah, may Allaah be please with him, that Allaah's Messenger (peace be upon him) said: "By Him in whose hand Muhammad's soul is (i.e., God, Allaah), there is none from amongst the Jews and the Christians (of these present nations to whom I have been sent) who hears about me and then dies without believing in the message with which I have been sent (i.e. Islamic monotheism), but he will be among the dwellers of the Hellfire." (Sahih Muslim, Book of Faith, #240).
Thus, your objectives in entering Islam are to save yourself from being among the permanent dwellers of Hell in the Hereafter, and to achieve the fantastic reward of the bliss of Heaven, the vastness of which is greater than that of the earth and the skies. Your overriding motive for accepting Islam should not be emotions stemming from your relationship with the Muslim man with whom you are in love. Your embracing Islam is something necessary for yourself whether you marry this man or not.
Secondly, obeying God (Allaah) and His Prophet Muhammad (peace be upon him) has a higher priority than your closest relative and most beloved dear one even if it is your mother or your spouse or anyone else. The Prophet of guidance has said : "There are three qualities, for which whoever is characterized by them will relish the sweetness of faith: one to whom Allaah and His Messenger are dearer than all else; one who loves a man only for Allaah's sake; and one who abhors returning to apostasy after Allaah has rescued him from it as he abhors being cast into Hell." (Sahih al-Bukhari, Book of Faith, #15).
He also said: "No worshipper (and in the hadeeth narrated by 'Abdul-Warith, no person) is a truthful believer, until I am dearer to him than the members of his household, his wealth and the whole of mankind." (Sahih al-Bukhari, Book of Faith #14).
I ask Allaah to hasten you to Islam and to help you firmly establish yourself in it, and to grant you a righteous and successful marriage as well as a blessed family. Indeed, Allaah is the One who guides to the path of truth, success, and righteousness.
Please see Subject area :Issues Relevant to New Muslims and Accepting Islam.